ES2366734T3 - INTRODUCTION SYSTEM EQUIPPED WITH A SELF-EXPANSIBLE BRAIDED STENT. - Google Patents

Abstract

An insertion system with a self-expanding braided stent (11) for implantation in a blood vessel has an outer sleeve (12) with a distal end (14) and a proximal end. An inner sleeve (16) arranged in the outer sleeve (12) is displaceable relative to the latter and protrudes, with a handling section, from the proximal end of the outer sleeve (12). Moreover, at the distal end (15), there is a tip (18) which is securely connected to a stent support (24) on which the braided stent (11) is arranged in its loaded state. The stent support (24) is arranged to be displaceable relative to the inner sleeve (16).

Description

The present invention relates to an introduction system with a self-expanding braided stent, intended to be implanted in a blood vessel, with an outer shell having a distal end and a proximal end on which a movable inner sleeve is disposed in relation to the outer shell that protrudes with a manipulation segment of the outer shell at its proximal end, and with a tip disposed at the distal end that is fixedly connected with a stent support on which the braided stent is arranged in its loaded state.

The applicant of the present invention knows an introduction system of this type existing in the market.

A stent means a radially expandable stent that constitutes a typical intravascular implant that is implanted transluminally and widens or expands radially after being inserted percutaneously. Stents are used, for example, to strengthen blood vessels and prevent restenosis in the vascular system after a previous angioplasty. In addition, they are also implanted in arteries to treat aneurisms.

These stents can be self-expanding or be expanded by a radial force exerted from the inside, for example, when mounted on a balloon.

Depending on the type of application, the most diverse stents are used. The present application deals with the application of so-called braided stents as they are known, for example, by patents DE 197 50 97 A1 or DE 103 35 649 A1.

A braided stent is a metallic stent that is manufactured as a so-called taffeta ligament tissue. It consists of a hollow body that can be extended in the longitudinal direction whose jacket is a braid of multiple filiform elements that cut at a braiding angle a plane perpendicular with respect to the longitudinal direction in the expanded state of the braided stent. During its strain a braided stent undergoes a large modification in its length, the longitudinal modification being the greater the larger the larger the initial diameter and the smaller the initial braiding angle.

For its implantation, this braided stent is stored in an elongated way in a so-called introduction or applicator system that is introduced percutaneously in the body in a suitable place, for example, in the femoral artery and transluminally conducted to the blood vessel where the stent is to be released The introduction system and the stent are often equipped with radiological markers with which the positioning and release of the stent can be controlled in situ.

In stents that do not undergo a modification of their length when they are released, or only a very small modification, the position of the stent to be implanted can be checked without problems, which is why there are also the most diverse introduction systems for these stents that expand only radially.

In braided stents, however, there is the problem that they shorten greatly when released. With a braiding angle of 40 °, for example, the relationship between the length of the stent in the loaded state in the introduction system and the length of the stent in the expanded state, that is, in the free state is, for example, 1 , 5: 1. If the braiding angle α decreases, this ratio will be further increased, and the ratio can be 4: 1 to 6: 1 with a braiding angle of α = 10º. It is worth mentioning in this context that the decrease in length also naturally depends on the diameter of the stent in its loaded state and the diameter of the stent in its released state.

This means that the braided stents are extremely extensible, being able to store mass, so to speak, in its elongated form, that when contracting the stents provides a dense and rigid functional zone as described exhaustively in the aforementioned DE 103 35 649 A1 patent .

Braided stents with which shortening of this type has to be taken into account, so far they are only released with little precision of positioning in the blood vessel. However, the positioning of a stent in the desired place within the blood vessel constitutes a critical factor that significantly determines the success of the medical intervention. The area within the blood vessel in which the stent is to be expanded is usually difficult for a doctor to access.

The stent has to be positioned, for example, in the area of an organ or, in the case of the carotid artery, in the area of the cerebral arteries, having to be placed there, where appropriate, only a relatively short stent. Due to the large decrease in length when releasing a braided stent, with conventional systems a large release length is also needed as is the case, for example, in the system available in the market.

In the known introduction system, the braided stent is located in its loaded state on the stent support, that is, extremely elongated proximally from the tip, and the stent support is fixedly connected with the inner sleeve. In this situation, the stent is pressed radially inwards by the outer shell and held in its elongated shape.

To deposit the braided stent, the inner sleeve and, therefore, the stent support are retained, as well as the tip that is attached to it and that should not be displaced during release. Then the outer shell of the tip is carefully removed, so that the stent is gradually released. As the stent is being released, it contracts in the direction of the outer envelope, that is, it moves away from the tip that, due to the inner sleeve, maintains its position with respect to the blood vessel in a fixed way. When the outer shell is removed, the stent that is gradually released and expands radially, but contracts in a longitudinal direction, first follows the outer shell until such a section of the braided stent has been released that it braces firmly against the wall inside the blood vessel

It follows from all this, however, that the tip of the introduction system must be advanced distally well above the release position provided for the braided stent in order to make the correct positioning possible. In the known introduction system, this is several centimeters, which translates into a release length that is not tolerable, especially when the braiding angles are small. Especially when a relatively short stent has to be positioned in the vicinity of an organ or cerebral arteries, there is a danger that the most advanced tip causes damage to the organ or cerebral artery.

Another drawback of the known introduction system consists in the fact that it is difficult to modify the position of the braided stent inside the blood vessel by manipulations in the outer envelope. If the operator has introduced the introduction system too much or not enough, he can no longer correct the final position of the braided stent with the known introduction system. If you find that the braided stent will be released too much above or below the expected deposition point, you will have to remove the braided stent again which is only admitted in emergencies and not more than twice with the known introduction system. To reload the braided stent to the introduction system, the outer shell is now attached, while the inner sleeve is carefully pulled back. However, this "recharge" is only possible as long as no more than 50% of the braided stent has been released.

In the known introduction system it is therefore disadvantageous, on the one hand, that especially braided stents with small braiding angles cannot be placed sufficiently close to cerebral organs or arteries, while it is also disadvantageous that an exact positioning results extremely difficult.

EP 0 943 300 A1 discloses an introduction system for stents with an inner sleeve that is wrapped by an outer or withdrawal shell, the inner sleeve having retaining means, controlled from the outside, for example a inflatable balloon, after whose inflation the stent can be fixed in relation to the inner sleeve, and by whose deflation it can be released. Due to these retention means it should be possible to position the stent with greater precision.

In addition, US 5,700,269 discloses an introduction system for stents that for loading a stent is provided with a piston arranged with displacement capacity on a stent support. The introduction system also has an outer shell by means of which the stent can be released by simultaneously exerting a counterforce with the piston. The introduction system disclosed in this document also presents closing mechanisms with which the inner sleeve can be fixed with respect to the stent support to release it, as well as a mechanism with which the device can be fixed. inner sleeve with respect to the outer shell to load the stent into the system.

US 6,350,278 discloses an introduction system for a prosthesis, comprising a stent support and an outer shell that compresses the stent. The introduction system may also have another envelope in which the combination of stent support and outer envelope is housed.

Finally, an introduction system for a stent with a withdrawal sleeve and a stent support fixedly connected with a pusher is disclosed by US 2005/0027345.

In view of this background, the present invention aims to develop the known introduction system in such a way that braided stents can be released in a simple way in terms of construction with improved positioning accuracy, preferably reducing the release length .

This objective is solved, according to the invention, by the introduction system, according to claim 1.

In this way the objective of the present invention is fully resolved.

The inventors of the present application have recognized that the problems of the known introduction system were due to the fact that the stent support was part of the inner sleeve. According to the invention, the stent support is now disengaged from the inner sleeve, so that the braided stent can be released by pulling the outer shell back, or by advancing the inner sleeve. Unlike the known braiding system, the inner sleeve is now allowed to move relative to the stent support.

That is to say that the stent is released, according to the invention, by the relative movement between the outer shell and the inner sleeve, therefore the operator can also manipulate the outer shell and modify the position of the stent in situ, when during release realizes that you have not introduced the introduction system sufficiently, or you have already introduced it too much.

At the beginning of the release of the braided stent, the tip of the outer shell is first released due to the relative movement between said outer shell and the inner sleeve, also leaving the distal end of the stent of the outer shell and expanding, that is, releasing from the tip. By advancing the inner sleeve the stent slides from its support, so that the stent can slide over the tip, since it is no longer coupled to the inner sleeve. During release it may be appropriate, first remove the outer shell slightly until the stent is released from the tip and then advance the inner sleeve. By working alternately with the inner sleeve and the outer shell or by the joint displacement of the inner sleeve and the outer shell, the stent can now be optimally positioned. The strong shortening during the release also causes in this case stent displacements that are not accurately predictable, but they can be compensated by relative movements in both directions.

Since the tip, moreover, only protrudes very little distally or does not protrude from the desired release site, there is also no danger of damaging blood vessels or organs located distally from the point of deposition.

In addition, the stent can be truly “structured” through this new possibility of manipulation, that is, it can be placed with different density at different points to create, for example, especially in the area of an aneurysm a very dense metal structure , while in front and behind the aneurysm something more stretched is placed so that it can be fixedly anchored in the inner walls of the body vessel.

Because the tip and support of the stent are decoupled from the inner sleeve, the new introduction system makes it possible, in a summary way, to position braided stents that are extremely shortened during their release also at points of the body vessels. accessible so far, with the new introduction system highlighting the properties of braided stents optimally, and braided stents can be structured or stretched properly during release.

In addition, a locking mechanism is arranged between the outer shell and the stent support which limits the displacement of the stent holder in relation to the outer shell in the distal direction to a maximum travel path.

With these measures, it is advantageous that the tip is not advanced too much when starting the release of the braided stent. In addition, it is advantageous that by continuing to release the braided stent by removing the outer shell, the tip is also not pulled back, that is, in a direction proximal to the interior of the stent being expanded. This measure also achieves that when the inner sleeve advances in relation to the outer shell, the stent support and, therefore, the tip remain in position, so that it is ensured that the braided stent can be slipped above the tip, so to speak.

This measurement makes it possible to deposit the braided stent in front of the initial position of the tip distally. For this purpose, the introduction system is introduced into the vessel until the tip is just in front of the point at which the released stent has to end distally. The outer shell is now removed a little, so that the tip and the braided stent are free at its distal end. The inner sleeve is then advanced, due to which the stent slides over the tip, so that with its distal end it comes into contact with the inner wall of the blood vessel distally from the tip. In certain cases, this order can also be reversed, so that the inner sleeve is first advanced until the braided stent rests on the blood vessel, followed by which the outer shell is removed or another relative movement is made between the outer shell and the inner sleeve.

Due to other relative movements between the outer shell and the inner sleeve, the braided stent can now be structured and properly deposited. From the point of view of the result, this means that the tip should not be advanced in areas of the body vessel in which the stent, once definitively released, will not be placed. This constitutes a decisive advantage over known release systems.

For this purpose, it is also preferred that the locking mechanism limit the displacement of the stent support in relation to the outer envelope in the proximal direction, when the stent support has been previously displaced in relation to the outer envelope in a predetermined travel path in the distal direction.

This measure has the advantage that even a fully released braided stent can be fully reloaded completely. When removing the stent which, for this purpose, is properly connected with the inner sleeve, the tip will not be dragged, but will be retained with respect to the outer shell by the locking mechanism, so that the relative movement between the braided stent and the inner sleeve is possible again. Because of this, the braided stent is placed back on the support and the locking of the tip prevents the braided stent from getting stuck between the outer shell and the tip.

It would certainly also be possible to facilitate the relative movement between the braided stent and the inner sleeve by means of different frictional forces or by means of springs, but it has been shown that with the reduced dimensions and diameters of the new introduction system, a merely mechanical blockage constitutes the best solution.

In the new introduction system of the tip and the stent support they are freely movable, both in relation to the outer shell, as well as in relation to the inner sleeve, the appropriate measures being able to limit the displacement capacity of the support of the stent with respect to the outer envelope both in the distal direction, as well as in the proximal direction. Although this limitation of the freedom of movement can be realized by elastic forces or frictional forces, according to a preferred embodiment of the invention locking mechanisms are used for this purpose.

In addition, it is also preferred that an unlocking mechanism is attached to the inner sleeve that releases the relative displacement of the braided stent relative to the outer shell, when there is a proximal displacement of the inner sleeve in relation to the outer shell.

In this case, it is advantageous that the blocking of the displacement of the stent support in relation to the outer envelope in the proximal direction is finally reverted, so that the tip can be withdrawn again to the outer envelope, if previously the stent has been placed again completely on the stent support. This makes possible a new positioning of the entire introduction system in the distal direction.

or proximal, as well as a simple and complete removal of the stent that had already been partially released, when during the operation the corresponding indications arise.

In this way, once the stent is completely released, it is possible to retract the tip proximally to the outer envelope before removing the introduction system from the body.

In this context it is preferred that the stent support is connected at its proximal end with a control bar that passes through the inner sleeve centrally and protrudes from it at its proximal end.

In this case it is advantageous that the control bar facilitates the displacement of the stent support and, therefore, of the tip in an active translatory manner with respect to the inner sleeve, as well as its retention, so that mechanisms can be dispensed with lock and unlock. The locking mechanism and, where appropriate, the unlocking mechanism may be arranged - whenever desired - also in the area of the proximal end, so that they remain outside the body. However, it must be borne in mind that in this construction the operator must also manipulate the control bar in addition to the outer shell and inner sleeve.

Alternatively, it is preferred, therefore, that the stent holder is mounted with its proximal end on the inner sleeve, which has a longitudinal groove through which a first stop connected with the outer shell that limits the displacement penetrates into the inner sleeve of the stent support in relation to the outer envelope distally to a maximum travel path.

This measure has the advantage that the freely movable tip, as well as the stent support attached thereto, are made without its own drive, so to speak, the stop acting only in the distal direction. The maximum travel path through which the tip can be moved relative to the outer envelope in the distal direction is determined by the axial distance between this first stop and a counter surface on the stent holder, when the stent is still in its loaded state .

In this case, it is preferred that the stent holder is fixedly connected with a distal control block that is mounted with displacement capacity in the inner sleeve and that is tractively connected with a proximal control block that is mounted with capacity. of displacement in the inner sleeve, this coming into contact with the first stop when there is a relative displacement of the stent support with respect to the outer envelope distally by the maximum displacement path.

This measure constitutes a constructive advantage, the locking mechanism that acts in the distal direction has a simple construction, both control blocks can be installed without problems both micromechanically.

Overall, it is preferred that the longitudinal groove has another stop associated with the stent support that comes into contact with a notch of the outer shell and limits the displacement of the stent holder relative to the outer envelope in the proximal direction, when the outer envelope has previously been displaced in relation to the outer envelope by the predetermined displacement travel in the distal direction.

This measure is also advantageous for construction. The additional stop is retained first in the inner sleeve and is only released when the inner sleeve has been displaced more distally in relation to the stent support, and then can fit into the outer shell through the longitudinal groove in the inner sleeve, This prevents the removal of the stent by removing the inner sleeve, the tip being dragged into the outer envelope in the proximal direction due to friction between the stent support and the stent.

It is preferred that the additional stop is arranged in the distal control block.

In this case it is advantageous that the longitudinal groove of the inner sleeve can serve to unlock the additional stop. Since if the inner sleeve is pulled back, the longitudinal groove disposed therein presses the additional stop inwardly with its distal end, so that it is released from the outer shell and now the tip is retracted to the outer shell. Since the additional stop is arranged in the distal control block, the unlocking is also performed automatically only when the inner sleeve has been almost completely withdrawn to its initial position and the braided stent is reliably returned on the stent support.

Generally, it is preferred that the distal and proximal control blocks are connected through a connecting wire that preferably passes through a guide hole disposed in the first stop.

Also for this technical measure simple construction is an advantage. Only two control blocks have to be arranged in the inner sleeve and the connecting wire cannot bend or form knots when guided through the guide hole, when the tip is finally removed. On the other hand, it is preferred that the distal and proximal control blocks are formed at opposite ends of a control sleeve that is mounted with displacement capacity in the inner sleeve, in whose control sleeve a longitudinal groove is arranged in which the first stop.

This is an alternative to the solution with the connecting wire, which also has a simple construction. Another advantage consists in the fact that the proximal control block is also displaced by removing the inner sleeve.

In many embodiments of the invention it is preferred that a sliding body is disposed on the stent support that can be moved in a longitudinal direction and that is located between the braided stent and the tip when the braided stent is loaded.

This measure has the advantage that the binding of the braided stent between the outer shell and the tip or the sliding body is surprisingly avoided, when the braided stent is reloaded. The sliding body therefore constitutes an alternative or complementary possibility with respect to the locking mechanism that limits the displacement of the stent support in relation to the outer envelope in the proximal direction when the stent support has been previously displaced in relation to the outer envelope by a predetermined travel path distally.

The inventors of the present application have recognized that, when removing the stent, this sliding body performs a kind of oscillating stirring movement between the tip and the braided stent, is temporarily trapped and then bounces in the direction of the tip, followed by which you can continue retracting the braided stent. Also in this way it is achieved that a braid stent almost completely released can be loaded again.

In this case it is preferred that the sliding body has an outer diameter that is greater than the difference between the inner diameter of the outer shell at its distal end and the double wall thickness of the braided stent.

This measure constitutes a constructive advantage since it ensures that the braided stent cannot get so easily stuck between the sliding body and the outer shell.

In addition, it is preferred that the sliding body has a rounded shape at its proximal end and that it is preferably made of a material that has a reduced coefficient of sliding friction with respect to the inner wall of the braided stent, the sliding body being preferably made of a elastic material.

These measures also lead by themselves or in combination with each other so that the braided stent does not get so easily stuck between the sliding body and the distal end of the outer shell, bouncing a sliding body that is made of an elastic material after being trapped eventually, because the elastic deformation energy that it has stored is almost completely transformed into kinetic energy and axially bounces in the distal direction.

In addition, it is preferred that the distal end of the outer shell is reinforced.

This can be done, for example, by radiological markers that reinforce the distal end of the outer envelope, so that it cannot widen. This also leads to the fact that the braided stent when removed cannot get stuck between the sliding body and the distal end of the outer shell.

It is generally preferred that a spacer is fixed on the inner sleeve manipulation segment that limits the introduction of the inner sleeve into the outer shell.

This measure constitutes a constructive advantage, since it simply provides a security element in the handling of the new introduction system. The spacer is arranged in such a way that it indicates when the stent is shortly before its definitive release. It must be removed before the release can be completed. As long as the operator does not remove this spacer, he or she cannot release the braided stent enough in its manipulations so that it cannot be removed again.

According to claim 1, the inner sleeve has at its distal end a support through which the braided stent is connected at its proximal end by traction with the inner sleeve.

This measure has the advantage that the stent can be reloaded without problems, which can be placed again on the stent support by pulling back the inner sleeve.

In this case, it is preferred that the support has a flange on which the proximal end of the braided stent is fixed by the outer shell.

This measure also has a constructive advantage, the flange constitutes a type of hook that releases itself when the inner sleeve is inserted so much into the outer shell that the flange protrudes from the distal end of the outer shell. For this purpose, if necessary, it is also necessary to first remove the spacer from the inner sleeve.

Another advantage of this construction consists in the fact that in this way the proximal end of the stent is not damaged as could be the case in a retention device from which the braided stent has to be removed.

In general, it is preferred that a channel intended to receive a guidewire centrally crosses the tip and the stent holder and that this guidewire be driven laterally outwardly through the longitudinal grooves of the inner sleeve and the outer shell.

This measure is known per se by the state of the art, the guidewire is placed before introducing the introduction system itself so as to be able to guide the tip of the introduction system safely through the meanders of the body vessels. This procedure is generally known as the Seldinger method.

Other advantages and features result from the subsequent description and the accompanying drawings.

Naturally, the characteristics mentioned above and those detailed below cannot be used only in the combination indicated in each case, but also in other combinations or by themselves, without abandoning the scope of the present invention.

Examples of embodiment of the invention are shown in the drawings and will be explained in more detail in the following description. The drawings show:

Fig. 1

an introduction system for a braided stent, in a schematic side view;

Fig 2

a schematic longitudinal section, enlarged, but not to scale through the distal section of the introduction system of Figure 1, according to a first embodiment;

Fig. 3

a second embodiment of the new introduction system, in a representation such as that of Figure 2;

Fig. 4

a third exemplary embodiment of the new introduction system in an embodiment like that of Figure 2, but with a partially released braided stent;

Fig. 5

a representation like the one in figure 4, but with the partially braided stent inserted again in the outer shell;

Fig. 6

a representation like the one in figure 4, but with the braided stent fully released;

Fig. 7

a fourth example of realization of the new introduction system, in a representation like that of the

figure 2;

Fig. 8

a representation like the one in figure 7, but with the braided stent partially released; Y

Fig. 9

a representation like the one in figure 8, but with the braided stent fully released.

In figure 1, an introduction system is indicated schematically with the numeral 10 with which a braided stent indicated with 11 can be implanted in a blood vessel.

The braided stent 11 is a self-expanding metallic stent that is manufactured as a taffeta ligament fabric as described in DE 103 35 649 mentioned above. Due to its twisted angle α = 10 ° the braided stent 11 has in its loaded state within the introduction system 10 as shown in Figure 1 a length that measures approximately five times more than the length of the braided stent in its released state .

The introduction system 10 has an outer envelope 12 at whose distal end 14 the braided stent 11 is arranged, as well as an opposite proximal end 15.

According to the usual nomenclature, the distal direction designates a direction that points towards the patient to whom the braided stent is to be implanted 11. The proximal direction accordingly designates a direction that points towards the operator.

In the outer envelope 12 an inner sleeve 16 with displacement capacity is disposed with respect to this, which protrudes at the proximal end 15 of the outer envelope 12, there presenting a handling segment 17.

At the distal end 14, the introduction system 10 has a tip 18 through which a guide wire designated with the reference 19 passes and protrudes laterally from the outer shell 12. With this guide wire the introduction system is introduced 10 in a patient's blood vessel, according to the well-known method of Seldinger, to release the braided stent there 11.

For the handling that is required for this purpose, a handle 21 with irrigation connection is generally arranged at the proximal end 15 of the outer shell 12, as is generally known in this type of introduction system. In the manipulation segment 17 of the inner sleeve 16, a handle 22 is also arranged through which the inner sleeve 16 can be moved in relation to the outer shell 12. A spacer 23 is indicated in front of the handle 22 in the distal direction. It serves as a stop when inserting the inner sleeve 16 into the outer shell and comes into contact with the handle 21.

The spacer 23 prevents the inner sleeve 16 from being inserted into the outer shell 12 so much that the braided stent is completely released. Therefore, it constitutes a safety element whereby the release of the braided stent 11 is prevented early. When the spacer 13 is removed, the inner sleeve is allowed to push further into the outer shell 12 to definitively release the braided stent 11.

In figure 2 the introduction system 10 of figure 1 is shown in a schematic longitudinal section in an enlarged schematic representation, but not to scale.

The tip 18 sits with its flange 18 ’inside the outer shell 12, so that the inside of the outer shell 12 is closed outwards. The tip 18 is followed in FIG. 2 in a proximal direction by a stent support 24 fixedly connected with the tip 18 and penetrating the inner sleeve 16, being there at its proximal end 25 fixedly connected with a bar of control 26 that centrally crosses the inner sleeve 16 and protrudes in the handle 22 of said inner sleeve 16, as shown in Figure 1 with the dashed line.

Both the tip 18 and the stent holder 24 are crossed by a channel 27 through which the guide wire 19, which extends outwardly passes through the longitudinal grooves 28, 29 and 31 of the control bar 26, the inner sleeve 16 and the outer shell 31, respectively. The grooves 28, 29 and 31 have been chosen in such a way that the guide wire 19 is not bent or trapped by moving the inner sleeve 16 in relation to the outer shell 12 and moving the stent holder 24 above the bar of control 26.

The inner sleeve 16 has at its distal end 32, a support through which the braided stent 11 is tensioned at its proximal end 22 with the inner sleeve 16. For this purpose at the distal end 32 of the inner sleeve 16 is arranged a flange 34 on which the proximal end 33 of the braided stent 11 sits and where it is retained by the pressure of the outer shell 12, directed radially inward.

In Figure 2 the construction has been designed in such a way that the outer envelope 12, the inner sleeve 16 and the stent holder 24 can be displaced from each other. To release the braided stent 11, the outer shell 12 is pulled back, for example, for which purpose the inner sleeve 16 and the control bar 26 are retained. In this way the tip 18 is released from the outer envelope 12, so that the braided stent 11 can be widened outwardly shortening simultaneously. Alternatively, the inner sleeve 16 can also be advanced first in relation to the outer shell 12 until the braided stent 11 rests on the blood vessel. Then the outer envelope 12 is pulled back to continue releasing the braided stent 11.

To continue releasing the braided stent 11, the inner sleeve 16 can be displaced in relation to the outer shell 12, due to which the braided stent 11 slides from its support 24. So that the friction generated between the braided stent 11 and the stent holder 24 does not cause the tip 18 to be pushed further distally, the control bar 26 is held together with the outer envelope 12 without displacement. This can be done by the operator, it being also possible to lock the control bar 26 and the outer shell 12 at the proximal end 15, if necessary.

If the release of the braided stent 11 does not develop satisfactorily, the braided stent 11 can be placed again on the stent holder 24 by again introducing the inner sleeve 16 into the outer shell 12. So that the tip 18 is not stuck with the stent retracted again in the outer envelope 12, the tip 18 is advanced through the control bar 26 to such a point in front of the outer envelope 12 and it is maintained there that the braided stent 11 can be placed again without problems in the outer envelope 12 and on the stent holder

24.

In this way, even the braided stent 11 can be fully recharged into the introduction system 10 and subsequently refold the tip 18.

The introduction system 10 can be completely removed again when a certain indication exists, it is also possible to correct only the position of the introduction system in the blood vessel and then release the braided stent 11 again.

Figure 3 shows in a representation like that of Figure 2 - but without the representation of the guide wire 19 - a second embodiment of the new introduction system, in which an active control of the translatory movement of the tip 18 and, therefore, of the stent holder 24 and in which, on the contrary, the tip 18 is freely movable with respect to the outer shell 12, as well as the inner sleeve 16. For this purpose, the stent holder 24 is mounted at its distal end inside the inner sleeve 16 in a distal control block 35, which has a proximal control block 36 associated. The distal control block 35 and the proximal control block 36 are made with rotational symmetry, but have a shoulder 37 and 38, respectively, by which they are guided in the longitudinal groove 28 of the inner sleeve 16, so that they cannot get stuck.

Through the longitudinal groove 28 penetrates a stop 39 formed in one piece with the outer casing 12 which is provided with a guide hole 41 through which a guide wire 42 passes by tension the distal control block 35 , as well as the proximal control block (36) with each other.

Between the stop 39 and the distal control block 36, a free section 43 is indicated by which the control block 36 and, therefore, the control block 35 can be moved with respect to the outer envelope 12 in the distal direction. Since the distal control block 35 is fixedly connected with the stent holder 34 and this, in turn, is fixedly connected with the tip 18, the inner width 43 also determines the maximum travel path through which the tip 18 can be displaced with respect to the outer envelope 12 in the distal direction.

The control blocks 35 and 36 together with the guide wire 42, as well as the stop 39, a locking mechanism that limits the displacement of the stent holder 24 in relation to the outer envelope distally to the maximum travel path 43 By sliding the braided stent 11 of the stent holder 34 the tip 18 therefore travels at most along the travel path 43 distally beyond the outer envelope 12 as shown schematically in the figure 4. Figure 4 shows in a representation like that of Figure 3 another embodiment of the new introduction system, however, the braided stent 11 is partially released, so that it protrudes with its distal end 44 distally by on top of tip 18. This is achieved if, once the insertion system in the vessel is positioned, the outer envelope 12 is pulled back first along the path d and displacement 43, or the inner sleeve 16 is advanced with respect to the outer shell 12 distally, so that the tip 18 is located distally in front of the outer shell 12 along the travel path 43. Then it slides a little to bit the braided stent 11 of the stent holder 24 by the distal advance of the inner sleeve 16, so that the stent widens radially and moves with its distal end 44 above the tip 18 in the distal direction.

If, in the situation shown in Figure 4, the outer envelope 12 is pulled back, the braided stent 11 will widen more in the proximal direction, but cannot be shortened much because it is retained both at its distal end 44, as well as at its proximal end 33. To now arrange the braided stent 11 in a very dense manner, that is, to give it the possibility of contracting to the maximum in the axial direction, not only will the outer envelope 12 be pulled back, but simultaneously or in its place also progresses the inner sleeve 16, so that, as it were, stent material is still supplied from the still stored area of the braided stent 11.

In this way it is possible to deposit a braided stent 11 optimally in a vessel by the relative displacement of the outer shell 12 and the inner sleeve 16, and by means of the corresponding manipulation it is possible to alternately create areas where the braided stent 11 it is densely placed and areas where it is placed less dense, as is medically desired.

The introduction system 10 offers this possibility because the tip 18 is freely movable with respect to the inner sleeve 16. When the inner sleeve 16 is displaced distally, according to Figure 4, this does not change the position of the tip 18. But if the outer envelope 12 is displaced in the proximal direction, the tip 18 will also be pulled back in the proximal direction. In this way, it is possible to approach the tip 18 directly to an organ or, for example, to a cerebral artery and by releasing the braided stent 11 push it even beyond the tip 18 distally.

This directed positioning and directed placement of the braided stent in the blood vessel was not possible with known introduction systems.

In Figure 4 it can be seen on the right that in addition to the first stop 39 there is also a flange 45 that is connected with the outer shell 12 and facilitates an even better guidance of the guide wire 42 inside the inner sleeve 16.

If, in this situation, the braided stent 11 is partially or totally retracted in the outer shell 12, there is a danger that due to friction between the braided stent 11 and the stent holder 24, it is displaced in proximal direction, so that the braided stent 11 can get stuck between the outer shell 12 and the tip 18. To avoid this it is shown in Figure 4 that a sliding body 46 is arranged on the stent holder 24 which, when the stent Braided 11 is fully charged, sits between the tip 18 and the distal end 44 of the braided stent 11 inside the outer shell 12.

The sliding body 46 is made of an elastic material and made rounded at its proximal end

47

In figure 5 it is shown in a representation like that of figure 4 how the sliding body 46 prevents the braided stent 11 from getting stuck when retracting it in the outer envelope 12. For this purpose, the sliding body 46 has, on the one hand, an outer diameter 49 which is greater than the difference between the inner diameter of the outer shell 12 at its distal end 14 indicated by reference 51 and twice the wall thickness of the braided stent 11 indicated by reference 52.

This arrangement ensures that the sliding body 46 remains distally away from the distal end 14 of the outer shell 12 when the braided stent 11 is removed proximally, so that the danger of the braided stent 11 getting stuck is reduced.

Furthermore, the sliding body 46 is made of a material that has a reduced coefficient of sliding friction with respect to the inner wall 48 of the braided stent 11, which also implies that the sliding body 46 of Figure 5 is not displaced in the proximal direction.

If the sliding body 46 also moves in the distal direction, it will be deformed due to its elasticity by the braided stent and this deformation energy will be periodically discharged causing the sliding body 46 to bounce in the distal direction which causes an amplitude of oscillation indicated with the reference 53.

So that in the position of the sliding body 46 shown in Figure 5 the distal end 14 of the outer shell 12 does not widen, which could cause a jam despite the elasticity of the sliding body 46, the outer shell 12 is reinforced in its distal end 14, presenting a radiological marker 54 that contributes to the reinforcement of the outer envelope material 12.

In other words, by retracting the braided stent 11 in the outer shell 12 the sliding body 46 oscillates between the position shown in Figure 5 and the position shown in Figure 4 and thus prevents the braided stent 11 from getting stuck, it can be completely retracted to the outer envelope 12.

A suitable material for the sliding body 46 is Teflon, the outer shell 12, as well as the stent holder 24, are preferably made of a thermoplastic material, while the inner sleeve 16 may be partially made of stainless steel.

The diameter 49 measures, for example, 1.4 mm, the inner diameter 51 is 1.5 mm and the wall thickness 52 measures 0.2 mm. The braided stent will then have in its expanded state, for example, a length of 40 mm and an outer diameter of 6 mm with a braiding angle of α = 10 °.

Figure 6 shows the introduction system 10 of Figures 4 and 5 in a state in which the braided stent 11 has been completely released. When the inner sleeve 16 is pulled back the distal control block 35 finally comes into contact with the distal end 32 of the inner sleeve 16 and thus retracts the tip 18 again to the outer shell through the stent holder 24. In This position shown in Figure 6, the introduction system 10 can be removed from the blood vessel by the guide wire 19.

According to a specific embodiment, the introduction system of Figures 4 to 6 can comprise an outer shell 12 having an outer diameter of 2.0 mm, an inner diameter of 1.55 mm and a length of 1550 mm. The outer shell 12 is made of polytetrafluoroethylene (PTFE) / block polyether amide (PEBA) and is reinforced or co-extruded, for example, inside by PTFE and outside by polyamide (PA).

Then the inner sleeve 16 has, for example, an outer diameter of 1.4 mm, an inner diameter of 0.4 mm and a length of 200 mm and is formed by a combination of stainless steel (1.4301 / 1.4310) and a material resistant to pressure such as polyether ether ketone (PEEK).

The stent holder 24 has an outside diameter of 0.6 mm, an inside diameter of 0.4 mm, as well as a length of 200 mm, and is made of polyimide (PI). The sliding body 46 has an outer diameter of 1.5 mm, an inner diameter of 0.7 mm, as well as a length of 2 mm, and is made of PTFE, PEEK or polyoxymethylene (POM).

In figure 7, another embodiment of the new introduction system is shown in a representation like that of figure 2.

While in the exemplary embodiment of Figures 4 to 6 the sliding body 46 prevents the braided stent 11 from being stuck in the tip 18 when retracted to the outer envelope 12, according to the embodiment example of Figures 7 to 9, a sliding body 46 is needed, in this case the distal control block 35 and the proximal control block 36 are formed in a control sleeve 55 which is mounted with displacement capacity in the inner sleeve 16. The control sleeve 55 has a longitudinal groove 56 which is associated with the longitudinal groove 28 and through which the stop 39 penetrates inside the control sleeve 55. This again ensures the maximum travel path through which the tip 18 can be moved with with respect to the outer envelope 12 in the distal direction.

In order to prevent the tip 18 from unintentionally retracting in the proximal direction, another stop 57 is arranged in the distal control block 35 which in its position shown in Figure 7 is pressed radially inwardly and rests on the sleeve inner 16. This additional stop 57 fits into the position shown in Figure 8 in a notch 58 in the outer envelope 12, thereby preventing displacement of the distal control block 35 and, therefore, of the stent holder 24 thus as of tip 18 in the proximal direction.

The position shown in Figure 8 is adopted at the time when the tip 18 has been displaced distally by a predetermined travel path indicated in Figure 8 with reference 43 ’. This predetermined travel path 43 'is insignificantly shorter than the maximum travel travel 43 shown in Figure 4. Even if now in the situation of Figure 8 the inner sleeve 16 is displaced proximally, it will place the braided stent 11 on the stent support 24. Despite the friction between the stent support 24 and the braided stent 11, the stent support 24 is not displaced in the proximal direction since this is prevented by the additional stop 57.

However, it is possible to retract the tip 18 completely back to the outer envelope 12 since, by continuing to move the inner sleeve 16 in the proximal direction, it finally runs into the distal end 59 of the longitudinal groove 28 against the additional stop 57 pressing it radially inwards, so that it returns out of the notch 58 as shown in Figure 9 where the braided stent 11 has already been completely released, so that the tip 18 retracts completely to the outer envelope 12 to be able to extract the introduction system from the vessel.

Claims (19)

1. Introduction system with a self-expanding braided stent (11), intended to be implanted in a blood vessel, with an outer envelope having a distal end (14) and a proximal end (15), in which a sleeve is arranged internal (16) movable in relation to the outer envelope (12) protruding with a manipulation segment (17) of the outer envelope (12) at its proximal end (15), and with a tip (18) disposed at the end distal (14) which is fixedly connected with a stent support (24) having a distal end and a proximal end and on whose distal end the braided stent (11) is arranged in its loaded state; wherein the stent support (24) is disposed with displacement capacity in relation to the inner sleeve (16) and penetrates with its proximal end into said inner sleeve (16); wherein the inner sleeve has at its distal end (32) a support through which the braided stent (11) is tensioned at its proximal end (33) with the inner sleeve (16); characterized in that a locking mechanism that limits the displacement of the stent support is arranged between the outer shell (12) and the stent support (24) (24) in relation to the outer envelope (12) distally to a maximum travel path (43).

2.

Introduction system according to claim 1, characterized in that the locking mechanism limits the displacement of the stent support (24) in relation to the outer envelope (12) in the proximal direction, as long as the stent support (24) has been previously displaced in relation to the outer envelope (12) by a predetermined travel path (43 ') in the distal direction.

3.

Introduction system according to claim 1 or 2, characterized in that an unlocking mechanism is attached to the inner sleeve (16) that releases the relative displacement of the stent support (24) with respect to the outer envelope (12) when there is a proximal displacement of the inner sleeve (16) in relation to the outer shell (12).

Four.

Introduction system according to one of claims 1 to 3, characterized in that the stent support (24) is connected at its proximal end (25) with a control bar (26) that centrally crosses the inner sleeve (16) and protrudes at the proximal end (15) of the inner sleeve (16).

5.

Introduction system according to one of claims 1 to 3, characterized in that the stent support (24) is mounted at its proximal end (25) on the inner sleeve (16) having a longitudinal groove (28) through the which a first stop (39) connected to the outer shell (12) penetrates the inner sleeve (16), which limits the displacement of the stent holder (24) in relation to the outer shell (12) distal to the path of maximum displacement (43).

6.

Introduction system according to claim 5, characterized in that the stent support (24) is fixedly connected with a distal control block (35) that is mounted with displacement capacity in the inner sleeve (16) and traction connected with a proximal control block (36) that is mounted with displacement capacity in the inner sleeve (16) and comes into contact with the first stop (39), when a relative displacement of the stent support (24) occurs with respect to the outer envelope (12) distally along the maximum travel path (43).

7.

Introduction system according to claim 5 or 6, characterized in that the longitudinal groove (28) has another stop (57) associated that is connected to the stent support (24) and comes into contact with a notch (58) arranged in the outer envelope (12), limiting the displacement of the stent support (24) in relation to the outer envelope (12) in the proximal direction, if the stent support (24) has previously been displaced in relation to the outer envelope (12) by the predetermined travel path (43 ') in the distal direction.

8.

Introduction system according to claims 6 and 7, characterized in that the additional stop (57) is arranged in the distal control block (35).

9.

Introduction system according to one of claims 6 to 8, characterized in that the distal and proximal control blocks (35, 36) are connected to each other through a guide wire (42) which preferably extends through a hole guide (41) arranged in the first stop (39).

10.

Introduction system according to one of claims 6 to 8, characterized in that the distal and proximal control blocks (35, 36) are formed at opposite ends of a control sleeve (55) mounted with displacement capacity in the inner sleeve ( 16), in whose control sleeve a longitudinal groove (46) is arranged in which the first stop (39) fits.

eleven.

Introduction system according to one of claims 1, 5, 6, 9 or 10, characterized in that a sliding body (46) is arranged on the stent support (24) that can be displaced longitudinally and is located between the braided stent ( 11) and the tip (18) when the braided stent (11) is loaded.

12.

Introduction system according to claim 11, characterized in that the sliding body (46) has an outer diameter (49) greater than the difference between the inner diameter (51) of the outer shell (12) at its distal end (14) and the double wall thickness (52) of the braided stent (11).

13.

Introduction system according to claim 11 or 12, characterized in that the sliding body (46) has a rounded shape at its proximal end (47).

14.

Introduction system according to one of claims 11 to 13, characterized in that the sliding body

(46) is made of a material that has a reduced coefficient of sliding friction with respect to the inner wall (48) of the braided stent (11). 15. Introduction system according to one of claims 11 to 14, characterized in that the sliding body (46) is made of an elastic material.

16.

Introduction system according to one of claims 11 to 15, characterized in that the distal end (14) of the outer shell (12) is reinforced.

17.

Introduction system according to one of claims 1 to 16, characterized in that a spacer (23) is fixed on the handling segment (17) of the inner sleeve (16) which limits the introduction of the inner sleeve (16) into the outer shell (12).

18.

Introduction system according to one of claims 1 to 17, characterized in that the inner sleeve support (16) has a flange (34) on which the proximal end (33) of the braided stent (11) is fixed by the outer shell (12).

19.

Introduction system according to one of claims 1 to 18, characterized in that a channel (27), which is intended to receive a guide wire (19), passes centrally through the tip (18) and the stent support (24) and this guide wire exits laterally through longitudinal grooves (29, 31) of the inner sleeve (16) and of the outer shell (12).